[FIX] account_ebics - Stop camt split on an invalid XML file

The error was noted but processing went on with root.nsmap, raising an
AttributeError. Unparseable content now also yields the "Invalid XML
file." notification instead of an XMLSyntaxError.

account_ebics/models/ebics_file.py

@@ -568,10 +568,14 @@ class EbicsFile(models.Model):
         """
         datas = []
         file_data = base64.b64decode(self.data)
-        root = etree.fromstring(file_data, parser=etree.XMLParser(recover=True))
+        try:
+            root = etree.fromstring(file_data, parser=etree.XMLParser(recover=True))
+        except etree.XMLSyntaxError:
+            root = None
         if root is None:
             message = self.env._("Invalid XML file.")
             res["notifications"].append({"type": "error", "message": message})
+            return datas
         ns = {k or "ns": v for k, v in root.nsmap.items()}
         camt_variant = ns["ns"].split("camt.")[1][:3]
         variant_tags = {